Process of removing soaps from asphaltic still bottoms and purifying the same



Oct. 6, 1936. H. T. TERRELL E1- Al.

PROCESS OF REMOVING SOAPS FROM ASPHALTIC STILL BOTTOMS AND PURIFYING THESAME Filed April 15, 1935 Patented Oct. 6, 1936 PB0ESS 0F REMOVING SOAPSFROM AS- PHALTIC STILL BOTTOMS AND PURIFY- lNG THE SAME Basson T.Terrell, Edward M. Hughes, and Philip Y L. Carter, Chester, Pa.,assignors to Sun Oil' Company, Philadelphia, Pa., a corporation of NewJersey Applicaiinnnpru 15,1935, serial Nit-16,270 2 claims. (ci. s79)The present invention relates to a process for producing cutting oil andmore particularly to a process for producing cutting oil comprising ablend of lubricating oil and soaps of petroleum naphthenic acids, and tothe method of producing such soaps.

When distilling lubricating oils from a topped residue, or mazoot,derived from a coastal naphthenic or asphaltic base crude which has beentreated with caustic soda. before distillation, there is produced anasphaltic still bottom which contains soaps of petroleum naphthenicacids in considerable quantities. `Such a process is described andclaimed in the patent to Arthur E. Pew, Jr., No. 1,761,153, issued June3, 1930. In lthe processl outlined above and described and claimed inthepatent, the topped crude or ma-` zoot is treated with caustic sodabefore distillation for the purpose of converting any containedpetroleum naphthenic acids into their corresponding soaps or sodiumsalts. This procedure lis followed in order that the distillates.thereby produced will not contain the petroleum naphthenic acids,thereby rendering unnecessary excessive acid treatment andneutralizationof the distillates produced.

The petroleum naphthenic `acids, which are naturally contained incoastal and other similar I crudes, have boiling points whichapproximate those of the lubricating fractions in such crudes. It istherefore impossible to avoid distilling oi such petroleum naphthenicacids, if the topped crudes or mazoots are distilled without preliminarytreatment. The preliminary treatment with caustic soda solution,however, transforms any contained petroleum naphthenic. acids into theircorresponding soaps or sodium salts, which soaps have boiling pointsmuch higher than any 1,694,463, issued November 11, 1928, wherein theoils or asphaltic bottoms containing the soaps are converted by theaddition of water into an emulsion, the emulsion heated undersuper-atmospheric pressure to a temperature above the boiling point ofwater and the soap solution settled from the asphalt; or the lubricatingdistillates containing the fatty acids are treated with sulphuric acid,the precipitate drawn off and the remaining body of naphthenic acidcontaining oil treated with an alkali to form an emulsion. The emulsionso formed is then settled, and the soap and water layer withdrawn,leaving a soap-free mineral lubricating oil; To the soaps so extractedthere,is added a small proportion apl ufacture a cutting oil from thesame without re ducing the original starting material, or any of theintermediate products, to emulsion form.-

A better understanding of the invention will be had vby reference `tothe accompanying drawing whih'is a diagrammatic representation of onetype of equipment in which the present invention may be lcarried out. f

Referring now to the drav. ng:

A, B, and C represent agitators such as are usually used in petroleumreneries for the acid treatment and neutralization of lubricatingoils.

D 'represents' a distillation unit wherein the distilland is heated bymeans -of the latent heat of condensation of mercury vapor. 'Such anapparatus is described a'd claimed in the patent to Arthur E. PeW,.Jr.,No. 1,761,151, issued June 3, 1930.

E also represents an agitator of the 'same type as A, B, and' C.

'The balance of the equipment shown in the Vdrawing consists of storagetanks, run down tanks, condensers, coolers, and heatersv such as form apart of the equipment in any petroleum renery.

lso

y Referring, now more particularly to the drawing, the soap-containingasphalt bottom vsuch as derived from a distillation process, asdescribed and claimed in Pew Patent 1,761,153, are admitted to theprocess through line I under a pressure imposed by pump 2. These bottomsare fed to a manifold line 3,having valved branches 4, l. and 6 leadingto each of the agitators A B, and C, respectively. sulphuric acid isadmitted to the process from an acid ball, or any suitable source,.through valved line 'l to manifold l from which it is fed by means ofvalved branches l, I Il, and I I to each of agitators A, B, and C,respectively. 'I'he agitators A, B, and C are each provided with valvedoutlets I2, I3, and I4 leading to a manifold line I5 in which is placeda pump I6 for pumping the material from the agitators.

Leading into the manifold I5 is a valved line Il containing a pump I8which takes suction on a lubricating oil storage tank I9. The line Illeads through a heater or heat exchanger and thence to the distillationplant D. There is also provided a tank 2i, having a valved inlet 22,'and a valved outlet 23 containing pump 24. This tank may be used asstorage for a portion or all ot the material flowing from the agitatorsA, B. and C. and tank I9 toward the distillation unit D.

The distillation unit D consists of a vaporizer 25 having upper andlower portions separated by a flat plate 26. The material to bedistilled passes into the vaporizer 25 from line 21 leading from theheater 20. A pool of the material is maintained at one endiof thevaporizer 25 by means of the weir 28. The material to be distilledoveriiows this Weir and ilows in a lthin film downwardly over the plate28, being heated during its travel by means of the latent heat ofcondensation of mercury vapor which is admitted to the lower portion ofthe vaporizer 25 through line 29, the liquid mercury formed by thecondensation being withdrawn through lineI 30 and returned to themercury boiler (not-shown). Any

material which is unvaporized in the vaporizer 2l flows out through line3I which connects with the inlet end of the next vaporizer in series.For the present purposes, there would ordinarily be from 6 to 10 ofthese vaporizers in series. However, one only is shown in the drawingfor the purpose of `simplicity The vapors generated within the vaporizer23 are withdrawn through lines 32 which lead to a vapor manifold 33 fromwhich-in vturn lines above the vapor inlets 34, therev is placed anannular pan 36 and aseries'oi bubble trays 31, the

pan 3B providing a throat to permit the upward passage of uncondensedvapors. That section oi' the tower below the pan 33 also containsseveral bubble platesto aid in thepoper separation or liquid and vaporwithin that sction or the tower.

- That portion of the vapor which is condensed below the pan 36 is drawnoil' from the bottom of the tower through line 3 3 and is returned tothe inlet end or the vaporizer. Those vapors which pass up through thethroat in pan 33 are fractionally condensed. by means yof redux liquidadded to the toppf tbe tower. 'and run down over the plates in the towerand are withdrawn through line 3l and cooler 4l to' run down tank -4I,whence they are periodically `through valved line 42, containingpumplgand delivered to tank 44. The vapors which vare condensed in thetower 35 pass overhead-through line 46 to a condenser 43, whencetheyfpto ture within tower 35, and therefore the rate of cooling, ismaintained such as .to preclude the passing overhead and cooling of morevapors than are necessary to form the requiredv quantity 'of reflux. If,however, a superfluous amount of reflux accumulates in tank 41 it iswithdrawn to storage through valved line 43 by means of pump 50. Fromthe top oi reflux tank 41 there is a valved line 5I which leads tovacuum producing equipment, sincev it is desirable, if not necessary, tomaintain the various stills in the series D under absolute pressureswhich vary from stili to still, but are all very low. g

Leading from the bottom of tank 44 there is 'a valved line 52 containingpump 33. This line leads to and throughs. heater or heat exchanger 54.From the heat exchanger a line '55 leads to the top .of agitator E; Line56, for the con- A-ior the purpose of blowing the material withinagitator E. The bottom of the agitator E is provided with a valvedoutlet BI containing pump the material from 32 for the purpose offorcing agitator E to storage tank'33.

The apparatus just described is used as follows in carryingout thepresent process:

Asphaltic products, containing soaps of naphthenic acids, from alubricating oil distillation process are admitted through line I 'andany of its branch lines 4, 5, and 6 to one or all ot the agitutors A, B,and C. These bottoms are preferably heated to a temperature varyingbetween 300 and 500 1 1'. When a sumcient quantity of bottoms has beenadmitted to one 0r all oi. the agitators, depending on whether the ilrstportion oi the process is being run, as a batch process or a` Continuousone. 66 B. sulphuric acid (Q6-93% H2804) is added through lines 9, III,or II. acid so admitted is in a quantity not more suillcient(practically a quantity-not quite suillcient) to completely convert thecontained soaps to their corresponding petroleum naphthenic acids. Thisisy quite necessary. since an excess of sulphuric acid would have anexceedingly deleterious corrosive action on the succeeding eqgipment.After the proper quantity of acid has added, the contentsarel agitateduntil a reaction product. After the reactioniscom- 3 plete, theacidiied` bottoms are withdrawn through lines I2, I3, or I4' to line- I5by means of pump I3.y To the line I3 is also adde 15%l of a lubricatingoil distillate having, or example..

a cash oi 37o-385 F. a nre of, isa-445 F.. and

a saybqi; viscosity at 100l F., of 50o-03o seconds.

oil is preferably heated to about 400 F., or

the approximate temperature of the acidifled bottoms. The mixture soproduced is then passed .either'to tank 2I vor-directly tothedistillation` equipmmt D.

As explainedin the first part of vthe present are converted to theircorresponding acids. Even pecification, the soaps contained in thebottoms though the. acids have -a much lower lboiling point than theasphalt containing them and are therefore distillable from the bottoms,whereas the soaps have boiling points much too high to be distilledwithout cracking, the acids are not readily distillable without theadmixture of an oil such as, or similar to, that just described, sincethe asphalt exerts a sufficiently high partial pressure effect to makeit extremely dilcult to distill thev acids below cracking temperaturewithout also distilling oi a portion of the asphalts, or at leastcarrying olf a portion of the asphalt in entrainment. However, by theaddition of from to 15% of a lubricating oil as above described', it ispossible to readily distill these acids without cracking, due to thefact that the added oilexerts a partial pressureeffect, and is muchlower boiling than the asphaltic constituents or the acids beingdistilled. Since a certain proportion of lubricating oil is requisite inthe final product, the addition oi oil at this stage imposes only aslight added burden on the plant, which burdenis more than offset by theadded advantages obtained. In certain cases the asphaltic bottoms fed tothe process will contain some undistilled lubricating oils, in whichcase it will be unnecessary to add any oil as above described,

since the oil remaining in the asphalts will exertY vacuum to drive oi aportion of the oil and acids. -V

The dstilland unvaporized in this vaporizer is then passed, by means ofline 3|, to the next vaporizer in series. The vapors generated withinthe vaporizers 25 are withdrawn through risers 32, manifolds 33, andlines 34 to the towers 35, within the lower portion of which a smallproportion of the vapors are condensed and returned by means of. lines33 to the inlet end of the vaporizer wherein they were generated, theremaining portion passing up through the throats in pans 36 and being inthe major part condensed by contact with the reux liquid ilowingdownwardly over trays 31. The remaining portion passes through lines 45and condensers and coolers 46 to the reflux lines 41 the condensate within the reflux tank being withdrawn and returned through lines 48 to thetops of towers 35. The amount of vapors passed overhead is controlled bythe temperatures in the towers so as to provide, on condensation andcooling, just suincient reflux to condense the desired side streamswithin the towers 35. The side streams, which are withdrawn throughlines 39 from pans 35, are theA desired acids and oil distilledtherewith and are passed through coolers 40 to run down tam 4|. In -theproduction of the usual grade of cutting oil all ofthe distilled acidsare pumped from the ru'n down tank Il to a single storage tank u.However, incertain cases it may be desirable to segregate the variousfractions distilled and classify them as to viscosity or saponlilcationnumber for various other uses, or for making various grades of cuttingor emulsiable oils.

Generally the best results are obtained by lamount of lubricating oilremaining therein, or

the amount of lubricating oil added after acidiilcation of the bottoms.

As a specific example, the following inlet temperatures and absolutepressures will serve to demonstrate the method of distilling wherein abattery of seven stills was employed.

Still No. l 570 F. 18-14 mm'. Still No. 2 605 F. 13-11 mm. Still No. 3630 F. 11-8 mm. Still No. 4 650 F. 10-8 mm. Y Still No. 5 665 F. 10-8mm. Still No. 6 675 F. 9-6 mm. Still No. 7 680 F. 8-6 mm.

The amount of acids distilled from the bottoms as a whole, or obtainedin each cut. will. of course, vary slightly depending upon the crudefrom which the starting material was derived. The following, however,will serve as an example:

Still numbers No.1 No.2 No.3 No.4 No.5 No.6 No.1

Testa:

Soy. vis. at 210 F- 46 Saponiiition No. 55.9l

When the above acids were combined, the'total showed a viscosity of 75seconds Saybolt at 210 F., and a Saponication No. of 40.6.

The composite of these cuts is withdrawn from the tank M through line 52by means of pump 53, and is pumped through a heater 54 and line 55 tothe agitator E. The proper quantity of caustic soda solution of 35-41 B.(about 29- 36% NaOH) is then added through line 55. Agi-I tation s thencarried out by means of air admitted through line 50, or other suitablemeans, until lthe acids are completely saponiiled. The amount of sodiumhydroxide added, and itsA strength, will vary depending upon the watercontent of the acids, the water content desired in the nished material.and the saponiilcation value of the acids or mixture of acids and oil.Generally'it has been found that with a composite such as illustratedabove, 38 B. caustic soda in the proper proportions gives a producthaving the required characteristics. It is usually advisable to use aslight excess of caustic soda solution, so that the nished product willbe very slightly on the alkaline side. If the'saponied mixture containstoo much water, it is blown with air to remove the excess water content.

Aftersaponiflcation, a light mineral lubricating oil having a Sayboltviscosity of 10Q-115 seconds at 100 F. is added in amounts varying fromto 50%, depending upon the amount of soaps desirable in the finishedproduct, the viscosity desired inthe finished product, and theemulsifying qualities required. '.l'his oil is added by means of valvedline 51, the oil being drawn from tank 53 and pumped by means of pump53.

The nnished cutting oil (which is an emulsoid jor dispersoid systemitself before the addition of water) will have approximately thefollowing characteristics, 4depending'upon the amount-ot oil added inboth cases:

Light oil 40%lilhl cil soap and Wren and heavy y vy oil A. P. I.Gravity- -i 16. 3 17. 2 Flash F 340 3N) Fire F .v- 365 366 Vis. at 1(1)"F. S. 2753 1W Vis atl30FS m' lidi Vis,Bt210F S U-- 72 65 Pour test F.--+10 +5 1.61 1.38 Water 2. i l. 8 Alkalinity NaOH 0.(8 0.07 Sap. value fSap. equivalent mg. KOB '22 19 adding to said bottoms a mineral acid',thereby effecting the acidification Vot soaps, and adding also asumcient quantity of lubricating oil ot lower aosems -and'form amineral'oil and soap emulsion.

2. The process of producing a blend of lubri- .cating. oil andnaphthenic acid soaps from asphaltic bottoms containing naphthenic acidsoaps produced inthe distillation of naphthenic base oil inthe presenceofan alkali, which comprises adding to. said bottoms a mineral acid inan 'amount not :quite sumcient to completely acidity the soapsand addingalso lubricating oil, sub- Jecnng the resultant emulsion of asphalt, oiland naphthenic acids to distillation to vaporize the acldsand oil,condensingthe acid-oil vapors, and

adding to the condensate an alkali adapted to -convert the containedacids to soaps and forni a

